Three-position signal.



L. A. HAWKINS.

THREE POSITION SIGNAL.

APPLICATION FILED 11011.7, 1908.

1,003,902. Patented Sept. 19,1911.

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Witnesses: Inventor:

Laure nce Hawkins h Q I I 6? j y I fltty L. A. HAWKINS.

THREE POSITION SIGNAL.

APPLICATION mum nov. 7. 1908.

1,003,902. Patented Sept. 19,1911.

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Inventor: W|t1jes s% Laurence fLHawkins,

UNITED STATES PATENT OFFICE.

LAURENCE A. HAWKINS, F SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

THREE-POSITION SIGNAL.

To all whom it may concern:

Be it known that I, LAURENCE A. Haw- KINS, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Three-Position Signals, of which the following is a specification.

stopping the arm at caution position when moved from clear toward danger. The power required for stopping the signal is much greater than that necessary for holding the signal at clear or caution. Consequently, if the normal strength of-the slot arm is sufficient to stop the signal at caution when moving from clear toward danger, considerable energy is wasted while the signal is held at clear or caution. On the other hand, if the slot magnet is made only strong enough to hold the signal when cleared, it will be of insufficient strength to stop the arm at caution, unless the arm is caused to move through caution position very slowly, which is sometimes objectionable in practice.

By my invention I am enabled to strengthen the slot magnet to stop the arm at caution without increasing the normal strength of the magnet when the signal is at rest in either clear or caution positions. To accomplish this, I take advantage of the fact that when the ampere turns of an electromagnet are suddenly varied the magnetism itself varies more gradually. If the magnet core is not laminated, and if the magnet coils are wound on a copper spool, or any other short-circuited conducting body surrounds the magnet core, the change in magnetism is quite slow.

My invention consists in providing means for increasing the strength of the slot magnet above normal, while the signal is moving from clear to caution positions. The excess ampere turns are maintained until just before the signal reaches caution posi- Specification of Letters Patent.

Application filed November 7, 1908.

Patented Sept. 19, 1911.

Serial No. 461,461.

tion. If, then, the ampere turns are suddenly reduced to normal, the magnetism of the slot magnet, particularly if the magnet is slow acting, does not have time to be greatly reduced before caution position is reached and the semaphore arm stopped.

It is customary to provide the slot magnets, in signals of the type to which my invention relates, with two windings,one a high-resistance shunt winding which serves to energize the magnet for holding the signal at caution and clear; the other a lowresistance winding in series with the motor circuit which strengthens the slot magnet while the signal is being cleared. Such a series magnet may be employed for increasing the strength of the slot magnet when moving from clear to caution to stop the semaphore arm at caution. If the contacts controlled by the semaphore arm, and controlling the strengthening coils, are properly arranged, the circuit of the strengthening coils may be closed only when the signal is moving from clear to caution and not when it is moving from caution to clear. Furthermore, if the circuit of these coils is run through contacts of the track relay for the block at which the signal is placed, the strengthening circuit will never be closed, except when it is required for stopping the signal at caution, for, if the signal is to go from clear to danger, the contacts of the tack relay will then be open, so that the strengthening circuit will not be closed. The movement from clear to caution is not a common movement of the signal, but occurs only when a train backs into the block in advance, or enters that block from another track. Consequently the arrangements mentioned above, which prevent the closing of the strengthening circuit, except at the times when it is required for stopping the signal at caution in moving from clear toward danger, are of advantage in preventing unnecessary wasteof current.

My invention will best be understood by reference to the accompanying drawings, in which- Figure 1 shows a rear elevation of a signal adapted for operation in accordance with my invention; Fig. 2 shows a diagram of the controlling means and circuit connections; Fig. 3 is a detail of the slot mechanism; Fig. 4 shows a suitable arrangement.

of the contacts for strengthening the slot magnet; Fig. 5 shows a modified arrangement of the contacts; and Figs. 6, 7 and 8 show a still further modification.

Referring first to Fig. l, A represents an electric motor which drives through a suitable set of speed-reducing gears a gearwheel B, which is loosely mounted on the semaphore shaft 0, and serves as a driving member for the semaphore arm D which is fast on the shaft. E represents an arm fast to the semaphore shaft 0, and carrying a finger or catch 6 adapted to engage pins or stops 6 on the drive-wheel B so as to clutch the semaphore arm to the motor for driving the arm to caution and clear, and for holding the signal at clear and caution. The arrangement of the slot magnets controlling the finger or catch 6 is best shown in Fig. 3. F represents the main slot coils, which are high-resistance coils adapted for connection in shunt to the motor circuit. f represents low-resistance series coils adapted for 0011- nection in the motor circuit. f represents the armature which is attracted when the coil is energized. This armature is carried at the long end of lever e which is pivoted at 6 and the short arm of which is connected by a link 6 to catch 0 pivoted at 6 As long as the armature f is held attracted by the slot coils, the finger or catch a is held in the position shown. When the armature is released by the magnets, the outer end of catch a is allowed to move downwardly and to the left, as viewed in Fig. 3, so as to unclutch the semaphore arm from the stops on the drive-wheel. G represents the usual dash-pot.

For controlling the motor and slot coils, stationary contacts H and movable contacts it, carried by the semaphore shaft, are provided. In addition to these usual contacts, a stationary contact H and a contact h on the semaphore shaft are provided, as shown diagrammatically in Fig. 2; the construc tion of these contacts being shown in Fig. 4. Fig. 4 shows the contacts H. and 72. in the positions they occupy when the signal stands at caution. When the signal moves from caution to clear, the contact h, which is carried by the semaphore arm,'moves upwardly. The upper end of the insulating block carrying the contact 77/ consequently strikes contact H, deflecting it to the left as shown in dotted lines so that the contact 72. passes to the right of contact H and does not engage therewith. When clear position is reached the relative position of the contact H, wit-h respect to the contact h, is that indicated by the dotted lines at the bottom of Fig. t. When the contact 72. starts downward again as the signal. moves from clear to caution, the contact H is defiected toward the right, so that the contact it passes to the left of it and engages it, and maintains contact with it during the greater part of the movement from clear to caution. Just before caution position is reached, contact H springs back to the position shown in full lines on Fig. 4:, introducing a quick break between the two contacts. The relative positions of contacts H and h during their engagement are shown in dotted lines in Fig. 5 which also shows a modified structure referred to later.

Now, referring to Fig. 2, A represents the armature of the motor, a the main series field, and a a shunt field which is used for braking at clear position. The shunt and series slot coils are indicated by F and 7, respectively. The battery or other source of current is indicated at T. J is a track relay connected across the rails K of the block at which the semaphore is stationed. This relay controls the movement of the signal to danger, and from danger to caution. L represents the line relay, which is controlled by the signal a block in advance and controls the signal movement from caution to clear. M represents a resistance in circuit with the contact H. The stationary contact H and the movable contacts 71 are shown in Fig. 2 developed upon a plane surface, with the relative positions of the stationary contacts with respect to the movable contacts in the three positions of the signal being shown by three dotted lines.

The operation is as follows: The block K being occupied by a train and the track relay J deenergized, the semaphore arm is at danger and the contacts are in the position shown. When the train leaves the block, track relay J is energized, while line relay L is deenergized. A circuit is then closed from the upper terminal of battery I through the series slot coil f, through the series motor field a, motor-armature A, contacts H and 7t, and armature of track relay J to the lower terminal of the battery. A second circuit is also closed from the upper terminal of the battery I through the main slot coils F, contacts H and 72. and armature J to the lower terminal of the battery. The motor consequently starts and drives the signal to caution position. When caution is reached, the position of the stationary contacts H, relative to the movable contacts h, is that indicated by the middle dotted line. In this position the circuit of motor-armature A, and consequently of series slot winding f is broken, while the circuit of the shunt coils F is maintained closed for holding the semaphore arm at caution. When the train leaves the block in advance, the line relay L is again energized and the motor circuit is closed through the armature of the line relay and drives the signal from caution to clear. At clear position the motor armature is disconnected from the battery and is short circuited so that the motor acts as a braking generator to stop the signal at clear posignal is returned to danger.

sition, while the shunt slot coils F are maintained energized by a circuit through the armature of the line relay L. Owing to the arrangement of contacts 11 and h above explained, these contacts have not been brought into engagement with each other during the clearing operation above described. Now, if the track relay J is deenergized by a second train coming on the block, the circuits are all opened and the Although in moving from clear to caution the contacts H and h are brought, into engagement with each other, this has no effect, since the circuit of these contacts is open at the contacts of track relay J. If, however, instead of the track relay J being deenergized by a train entering a block, the line relay L is deenergized by a train backing into the block in advance, a circuit is closed by contacts i H and h almost as soon as the signal leaves clear position. This circuit connects the upper terminal of the series slot coils f through the contacts h and H, resistance M, and contacts of track relay J to the lower terminal of the battery I. This throws the series slot coils directly across the battery in series with the resistance M. This resistance is so proportioned as to permit suiticient current to How to bring the magnetism of the slot magnet up to saturation within the time that the contacts H and it remain in engagement. Just before reaching caution position, the contact H snaps away "from h, opening the circuit of the series coils j. The magnetism of the slot magnets does not immediately drop to normal, however, for the shunt winding F has had its circuit closed before caution position is reached, and acts not only to maintain the normal ampere turns on the slot magnets, but further, since this winding is short-circuited on the battery, it serves, even if the slot magnet is nototherwise constructed so as to be slow-acting, as a short-circuited winding to prevent any rapid change of flux in the slot magnet. Thus at the instant when the semaphore arm reaches caution position and the catch or finger e is brought into engagement with the next pin 6, the strength of the slot magnet is much above normal, so that it is able to stop the semaphore arm.

I The excess strength of the slot magnet, of

course, disappears in a few seconds, but remains long enough to serve its purpose. It will thus be seen that the excess of magnetic strength required for stopping the arm is obtained with out increasing the current consumption when the signal is at rest, and further, that the excess magnetizing current is never used except during the unusual nal movements which require the excess current for proper operation.

In order to reduce the Wear on the block which carries the contact h, the block itself may be made of metal as indicated in Fig. 5, and the contact h suitably insulated from the block. Still another arrangement is that shown in Figs. (3, 7 and 8, in which the contacts H and 11 are both stationary, and are moved into engagement with each other at the proper time by a movable block O, which is carried on the shaft 0, but which is not connected in circuit. \Vith this construction the contacts may be tipped with small blocks of carbon to reduce the burning, as indicated in Figs. (3 and 7 Fig. (3 shows the relative positions when the signal is at caution. In moving from caution to clear, block O moves upward, pushes the contact II to the left, as indicated in dotted lines and passes between it and the contact h without engaging the latter. \Vhen clear position is reached the block O has passed beyond contact H, so that this contact snaps back into its original position. TV hen the signal returns from clear to caution, the block moving downward shifts contact H to the right, as shown in Fig. 7, bringing it into engagement with h and maintaining it in engagement until just before caution position is reached. In Fig. 7 the normal positions of contact H and block 0 are shown in dotted lines.

Other suitable arrangements of the contacts will be obvious to those skilled in the art. irccordingly, I do not desire to limit myself to the particular construction and arrangement of parts here shown, but aim in the appemled claims to cover all modifications which are within the scope of my invention.

\Vhat I claim as new and desire to secure by Letters Patent oi the United States, is,-

1. A three-position semaphore signal, comprising an electric l'notor, a driving member driven by the motor, a semaphore arm, means For clutching said member to said arm to drive it from danger to caution and to clear and to hold said arm at caution or at clear and for luiclutching said arm to permit it to move from clear to caution and to danger, an eloctromagnet controlling said means. and means for increasing the strength of said electromagnetabove normal while said arm is moving from clear to caution for stopping said arm at caution.

2. A three-position semaphore signal, comprising an electric motor, a driving member driven by the motor, a semaphore arm, means for clutching said member to said arm to drive it from danger to caution and to clear and to hold said arm at caution or at clear and for unclutching said arm to permit it to move from clear to caution and to danger, an electromagnet controlling said means. a track relay controlling the movement of said arm to danger and from danger to caution, and means controlled by said relay for increasing the strength of said electromagnet above normal while said arm is moving from clear to caution for stopping said arm at caution.

3. A three-position semaphore signal, comprising an electric motor, a driving member driven by the motor, a'semaphore arm, means for clutching said member to said arm to drive it from. danger to caution and to clear and to hold said arm at caution or at clear and for unclutching said arm to permit it to move from clear to caution and to danger, an electromagnet controlling said means, and contacts in circuit with said electromagnet and controlled by said arm and arranged to be closed only while said arm is moving from clear toward caution.

i. A three-position semaphore signal, com prising an electric motor, a driving member driven by the motor, a semaphore arm, means for clutching said member to said arm to drive it from danger to caution and to clear and to hold said arm at caution or at clear and for unclutching said arm to permit it to move from clear to caution and to danger, an electromagnet controlling said means, contacts in circuit with said electromagnet and controlled by said arm and arranged to be closed only while said arm is moving from clear toward caution, and a track relay controlling the movement of said arm to danger and from danger to caution and having contacts in circuit with the first-mentioned contacts.

5. A three-position semaphore signal, comprising an electric motor, a driving member driven by the motor, a semaphore arm, means for clutching said member to said arm to drive it from danger to caution and to clear and to hold said arm at caution or at clear and for unclutching said arm to permit it to move from clear to caution and to danger, an electromagnet controlling said means, contacts controlled by said arm and arranged to be actuated only while said arm is moving from clear toward caution, a track relay controllingthe movement of said arm to danger and from danger to caution, and means controlled jointly by said contacts and said relay for increasing the strength of said electromagnet above normal while the arm is moving from clear to caution for stopping the arm at caution.

6. A three-position semaphore signal, comprising an electric motor, a driving member driven by the motor, a semaphore arm, means for clutching said member to said arm to drive it from danger to caution and to clear and to hold said arm at caution or at clear and for unclutching said arm to permit it to move from clear to caution and to danger, an electromagnet controllingsaid means, a winding on said electromagnet which is deenergized when the arm is being held at clear or caution, and contactsand connections arranged to energize said winding while the arm is moving from clear toward caution and to strengthen said magnet to stop the arm at caution.

7. A three-position semaphore signal, comprising an electric motor, a rotary driving member driven by the motor, a semaphore arm, a series of stops and a catch movable into and out of engagement with said stops, said stops and catch moving one with said driving member and one with said arm, an electromagnet cont-rolling said catch, and means for increasing the strength of said electromagnet above normal while the arm is moving from clear to caution for stopping the arm at caution.

8. A threeposition semaphore signal, comprising an electric motor, a rotary driving member driven by the motor, a semaphore arm, a series of stops and a catch movable into and out of engagement with said stops,

said stops and catch moving one with said driving member and one with said arm, and said stops being spaced forty-five degrees apart, an electromagnet controlling said catch, and means for increasing the strength of said electromagnet above normal while the arm is moving from clear to caution for stopping the arm at caution.

In witness whereof, I have hereunto set my hand this 6th day of November, 1908.

. LAURENCE A. HA WKINS. Witnesses:

BENJAMIN B. HULL, HELEN ORFORD.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. C. 

